Effect of Serum upon Tissues. 189 



The sections (all of about the same size and thickness) were 

 placed in small test tubes, each containing 1 c.c. of the serum 

 dilution. 1 c.c. of physiological salt solution was the constant 

 control. To each tube was added 1 c.c. of toluol and the whole 

 series incubated at 37. 5 0 C. for 18-21 hours. 



The staining was done by means of Delafield's hematoxylen 

 and eosin. All sections of a series were stained in an identical 



Delafield's hematoxylen I min. 



}/2 per cent, alcohol eosin 10 sec. 



85 per cent, alcohol 30 sec. 



Oil of origanum Until clear. 



Canada balsam mounting. 



manner. Fresh sections were treated by floating on a slide, 

 drying on blotting paper over the paraffin stove, then staining. 

 Boiled sections were transferred in the moist state to the various 

 solutions, as otherwise they are likely to float off the slide. We 

 have also employed the various fat stains and the Altmann 

 granule stain but have found the simple hematoxylen-eosin 

 adequate. 



The most striking changes are found in the nuclei. When 

 exposed to the action of cat serum up to a dilution of 1 : 30, no 

 nuclei are to be seen in the boiled sections. On fresh tissue, con- 

 trary to what might have been expected, this action was even 

 more marked, as no nuclei were visible at a dilution of 1 : 120 

 of the serum. The nuclei either had disappeared entirely or had 

 failed to take the stain. In addition the tissue appeared cloudy, 

 parboiled, and not infrequently cleavage lines ran through the 

 whole specimen. At times, as in the guinea-pig placenta to be 

 shown on the screen, the organ assumed a reticular structure, as 

 in specimens treated by the Spalteholz or Mall's digestion method. 

 At other times, the whole specimen appeared homogeneous, the 

 tissue becoming unrecognizable. Fibrous tissue as the trabecular 

 of the spleen and adventitia of vessels stand out distinctly, but 

 the nuclei seem to have disappeared. The appearances were very 

 similar to those observed in autolysis of organs. 



When we had established that the titre of activity of cat serum 

 remains constant, i. e., no nuclei in the boiled sections on exposure 

 to a dilution of 1 : 30 or I : 40 we injected a cat whose serum was 

 previously tested, with I gm. of fresh cat liver freed from blood, 



